Add checks for input arguments

Author: TomashKhamlai

app/code/Magento/CustomerGraphQl/Model/Resolver/Customer/Account/GenerateCustomerToken.php

@@ -29,7 +29,6 @@ class GenerateCustomerToken implements ResolverInterface
      */
     public function __construct(
         CustomerTokenServiceInterface $customerTokenService
-
     ) {
         $this->customerTokenService = $customerTokenService;
     }
@@ -45,6 +44,12 @@ public function resolve(
         array $args = null
     ) {
         try {
+            if (!isset($args['email'])) {
+                throw new GraphQlInputException(__('"email" value should be specified'));
+            }
+            if (!isset($args['password'])) {
+                throw new GraphQlInputException(__('"password" value should be specified'));
+            }
             $token = $this->customerTokenService->createCustomerAccessToken($args['email'], $args['password']);
             return ['token' => $token];
         } catch (AuthenticationException $e) {

app/code/Magento/CustomerGraphQl/etc/schema.graphqls

@@ -10,7 +10,7 @@ type Mutation {
 }
 
 type CustomerToken {
-    token: String @doc(description: "The new customer token")
+    token: String @doc(description: "The customer token")
 }
 
 type Customer @doc(description: "Customer defines the customer name and address and other details") {